This is not Sales vs Product. This is bad product management, full stop. It is not sales’ responsibility to define the product, it is product’s responsibility to do that, taking into account sales requests, market analysis, executive vision, user feedback and engineering feasibility. In any given situation it takes a lot of expertise and judgement (and often luck!) to know where they need to be focused. Trying to reduce actual product problems to some simple knob between caricatured role definitions will help no one except management consultants. In reality product management failure is very contextual to the problem at hand-—details matter.